Möller, Saffran

Abstract [en]

Background: To undergo a lower limb amputation is a traumatic experience affecting the individual on physical as well as psychological levels and often leading to limitations in a person´s daily life. Following an amputation individual often receive a prosthesis to address impairments in mobility and functioning. The mechanical properties of the prosthesis can vary, and the choice of specific components to include in the device has been demonstrated to influence patient outcomes. Studies investigating the relative effects of different prosthetic knee components have generally focused upon physical and biomechanical outcomes, providing a rather narrow view of health-related states in prosthetic users. There is a need to view health and wellbeing of prosthetic users from a broader perspective by evaluating outcomes that reflect a variety of different factors that can influence their functioning.

Aim: The overall aim of this thesis was to describe and compare functioning in individuals with a trans-femoral amputation or knee disarticulation and to evaluate the relative effects of using non-microprocessor-controlled prosthetic knees (non-MPK) or microprocessor-controlled prosthetic knees (MPK).

Methods: The four studies presented in this thesis used a cross-sectional, quantitative design with different types of data collection methods. These included self-report measures, capacity tests, a survey with two questionnaires and a measure of cortical brain activity during normal level waking and while performing a secondary task. One group of 42 individuals with lowerlimb amputations, using a prosthetic knee with or without microprocessor-control was included in the survey study. Another group of 29 individuals with a lower limb amputation, using a prosthetic knee with or without a microprocessor-control and a control group (n=16) participated in the remaining studies. Statistical tests were used to compare differences between groups using different knee joints, between prosthesis users and controls.

Results: Individuals using a non-MPK had lower self-reported mobility and balance confidence as well as poorer results on mobility tests compared to those using an MPK. Results revealed no significant differences in self-rated health, daily step count or general self-efficacy. Increased cortical brain activity was seen in frontal cortex in individuals using a non-MPK in single-task walking compare to the MPK group and controls. A significant increase in brain activity was also seen in prefrontal cortex in dual-task walking compared to single-task walking in those walking with an MPK and controls.

Conclusion: Combined results of all four studies suggest that persons provided with an MPK had better mobility, both self-rated and objectively evaluated, and better self-rated balance confidence than those who were using a non-MPK. Results also showed that an individual’s belief in their own ability was associated with the number of hours they use their prosthesis per week. Participants using a non-MPK had higher levels of cortical brain activity in the frontal cortex during walking, suggesting that the attentional demand required to walk was greater than for individuals using an MPK. Of particular interest for health professionals involved in prosthetic rehabilitation was the finding that significant increases in attentional demand were not always reflected in temporospatial gait parameters. This suggests that cognitive demands may not always be reflected in variables that are commonly evaluated in the clinical setting.

Abstract [en]

Purpose: To measure self-efficacy in a group of individuals who have undergone a lower-limb amputation and investigate the relationship between self-efficacy and prosthetic-specific outcomes including prosthetic use, mobility, amputation-related problems and global health. A second purpose was to examine if differences exist in outcomes based upon the type of prosthetic knee unit being used.

Method: Cross-sectional study using the General Self-Efficacy (GSE) Scale and the Questionnaire for Persons with a Transfemoral Amputation (Q-TFA). Forty-two individuals participated in the study. Twenty-three used a non-microprocessor-controlled prosthetic knee joint (non-MPK) and 19 used a microprocessor-controlled prosthetic knee joint (MPK).

Results: The study sample had quite high GSE scores (32/40). GSE scores were significantly correlated to the Q-TFA prosthetic use, mobility and problem scores. High GSE scores were related to higher levels of prosthetic use, mobility, global scores and negatively related to problem score. No significant difference was observed between individuals using a non-MPK versus MPK joints. Conclusions: Individuals with high self-efficacy used their prosthesis to a higher degree and high self-efficacy was related to higher level of mobility, global scores and fewer problems related to the amputation in individuals who have undergone a lower-limb amputation and were using a non-MPK or MPK knee. Implications for rehabilitationPerceived self-efficacy has has been shown to be related to quality of life, prosthetic mobility and capability as well as social activities in daily life. Prosthetic rehabilitation is primary focusing on physical improvement rather than psychological interventions. More attention should be directed towards the relationship between self-efficacy and prosthetic related outcomes during prosthetic rehabilitation after a lower-limb amputation.

Abstract [en]

Background: Individuals using a lower-limb prosthesis indicate that they need to concentrate on every step they take. Despite self-reports of increased cognitive demand, there is limited understanding of the link between cognitive processes and walking when using a lower-limb prosthesis.

Objective: The objective was to assess cortical brain activity during level walking in individuals using different prosthetic knee components and compare them to healthy controls. It was hypothesized that the least activity would be observed in the healthy control group, followed by individuals using a microprocessor-controlled prosthetic knee and finally individuals using a non-microprocessor-controlled prosthetic knee.

Study Design: Cross-sectional study.

Methods:: An optical brain imaging system was used to measure relative changes in concentration of oxygenated and de-oxygenated haemoglobin in the frontal and motor cortices during level walking. The number of steps and time to walk 10 m was also recorded. The 6-min walk test was assessed as a measure of functional capacity.

Conclusion: Individuals walking with a non-microprocessor-controlled prosthetic knee demonstrated an increase in cortical brain activity compared to healthy individuals. Use of a microprocessor-controlled prosthetic knee was associated with less cortical brain activity than use of a non-microprocessor-controlled prosthetic knee.

Clinical Relevance: Increased understanding of cognitive processes underlying walking when using different types of prosthetic knees can help to optimize selection of prosthetic components and provide an opportunity to enhance functioning with a prosthesis.